The present invention relates to a target for magnetron - sputtering systems consisting of a ferromagnetic alloy whose phase diagram exhibits a cubic and a hexagonal phase, whereby the hexagonal phase is present at the operating temperature of the target in a state of equilibrium but large portions of cubic structural components can still be present due to kinetic obstructions.
Permanent magnets are arranged behind the target (cathode) in magnetron - sputtering for optimizing the atomization process. This is carried out so that a magnetic field forms in front of the target in the discharge space. In this way, the field functions so that the discharge plasma is localized. The area of the target surface over which the plasma is localized is preferably sputtered, which forms an erosion trench at that location.
Basically, two problems occur thereby in ferromagnetic targets:
First, the magnetic flux of the permanent magnets is bundled in the target so that only a low flux can exit into the discharge space. This problem therefore requires the use of very thin ferromagnetic targets.
Second, the local cross-sectional decrease of the target during the sputtering (erosion trench) brings about an increasing magnetic flux directly over the erosion trench in the case of ferromagnetic targets. This causes a higher ionization probability of the sputtering gas to occur locally and a higher sputtering rate to occur locally, with the consequence that the erosion trench becomes very narrow, coupled with only a slight material yield of the target.
Improved magnetic field geometries and a higher magnetic field in the discharge space can be achieved by expensive target designs. Slots in the target vertical to the direction of the magnetic field can raise the magnetic resistance in the target and bring about a larger field in the discharge space (K. Nakamura et al. IEEE Transactions on Magnetics 18 (1982), p. 1080).
Kukla et al. (IEEE Transactions on Magnetics 23 (1987), p. 137) describe a cathode for ferromagnetic materials which consists of several individual targets arranged in two planes over each other in order to achieve a higher magnetron magnetic field. However, these designs are expensive and make the magnetron - sputtering more difficult.